초록 ▼

A controlled current inverter system forms the basis of an a.c. motor drive system for furnishing the motor load with a variable frequency, variable magnitude a.c. current from an inverter which is supplied from a variable d.c. current source by way of a d.c. link including an inductor. Torque is th

A controlled current inverter system forms the basis of an a.c. motor drive system for furnishing the motor load with a variable frequency, variable magnitude a.c. current from an inverter which is supplied from a variable d.c. current source by way of a d.c. link including an inductor. Torque is the control parameter employed in the system and the motor speed and torque are controlled through the control of motor flux and motor current, by maintaining a controlled ratio between the direct and quadrature motor currents, through separate control paths to the d.c. source and the inverter. A third control path functioning on the difference between the desired and actual motor flux serves as a modifier to the main control paths to improve overall operation and control. Means associated with the basic control paths provide for dynamic braking of the motor.

대표청구항 ▼

A control for an a.c. electric motor having a stator and a rotor spaced from the stator by a gap across which gap flux is produced in response to an electrical motor current of variable magnitude and frequency through windings associated with said stator, said control serving to control the electric

A control for an a.c. electric motor having a stator and a rotor spaced from the stator by a gap across which gap flux is produced in response to an electrical motor current of variable magnitude and frequency through windings associated with said stator, said control serving to control the electrical torque of said motor and comprising: (a) means to determine, with respect to the motor, the instantaneous electrical torque and the instantaneous angle between the gap flux and the motor current and to provide signals proportional thereto; (b) means to establish a torque reference signal proportional to a desired level of electrical torque; (c) means to compare said torque reference signal with said signal proportional to the instantaneous electrical torque and to generate a current error signal representative of any difference therebetween, said current error signal acting as the primary control parameter serving to vary the magnitude of the motor current; (d) means responsive substantially solely to said torque reference signal to derive an angle reference signal representative of the desired angle between the gap flux and the motor current; and, (e) means to compare said angle reference signal with said signal proportional to the instantaneous angle between the gap flux and motor current and to generate a frequency error signal representative of any difference therebetween and effective to vary the frequency of the motor current.